Conference Rationale: The overall goal of this application is to leverage AHRQ's large conference support mechanism to advance the science of diagnostic error reduction. Diagnostic errors (defined as missed, delayed, or wrong diagnosis) are an important, common, and costly problem but have been underemphasized in the patient safety field to date. Although recent increased attention to patient safety in ambulatory care settings has shed light on the impact of diagnostic errors, the difficulty of identifying and trackng these errors has slowed the pace of interventions to prevent them. Understanding and addressing the complex origins of diagnostic errors requires a multidisciplinary approach that coordinates the input of clinicians, human factors experts, informaticians, and cognitive scientists, as well as participation of important stakeholders such as payers, medical educators, patient advocates, and accrediting/credentialing organizations. Previous Conferences and Impact: The first Diagnostic Error in Medicine (DEM) conference was held in 2008 with the support of AHRQ. With continued support from AHRQ, the DEM conferences have evolved into annual meetings that serve not only as forums for groundbreaking research but also as means of bringing together researchers, practitioners, and noted speakers and experts to focus on issues that lie at the intersection of diagnostic reasoning and medical error. In addition to high-impact publications, work presented by DEM conference participants has attracted the attention of major media outlets including the Wall Street Journal and key organizations such as the AMA. Another significant outcome of these meetings has been the formation of a new, independent organization (Society to Improve Diagnosis in Medicine) dedicated to research, education, and awareness about diagnostic error. Continued support is crucial to stimulate scholarly multidisciplinary collaboration and to engage several key national stakeholders in the emerging field of diagnostic error. Conference Plan: Our plan for the DEM conference in 2013 will be a 2.5-day meeting preceded by half-day workshops on current topics in diagnostic error. A variety of session formats will be used to engage participants, including large-group presentations, small-group discussions, hot topics debates, a poster session, oral scientific abstracts, and breakout groups. The 2013 conference will be organized around three major themes: measurement of diagnostic error, reducing diagnostic error through improved process measurement, and achieving change. Speakers will be internationally recognized leaders from diverse disciplines. Meeting facilities and accommodations will be coordinated through an academic affiliate host. Subsequent meetings will follow the same general plan, with modifications based on participant feedback. Impact/ Deliverables: In addition to published conference proceedings and white papers, the conferences will provide a forum to establish research priorities in the field, develop educational curricula and foster interdisciplinary collaboration, with the ultimate goal of developing strategies to reduce diagnostic errors.